That state in which every part of space is supposed to be full of matter; -- opposed to vacuum. G. Francis. [1913 Webster]
A condition, as in an occupied room, in which the pressure of the air is greater than that of the outside atmosphere; as, a plenum may exist in a hall ventilated by a fan blower. [Webster 1913 Suppl.]

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OXFORD DICTIONARY

plenum, n.
1 a full assembly of people or a committee etc.
2 Physics space filled with matter.

Etymology

L, neut. of plenus full

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THESAURUS

plenum

Copernican universe, Einsteinian universe, Indian file, Newtonian universe, Ptolemaic universe, air, all, all being, all creation, allness, array, articulation, assemblee, assembly, assignation, at home, atom, atomic particles, ball, bank, brawl, brute matter, building block, buzz, catena, catenation, caucus, chain, chain reaction, chaining, chemical element, colloquium, commission, committee, component, concatenation, conclave, concourse, congregation, congress, connection, consecution, constituent, continuum, conventicle, convention, convocation, cosmos, council, course, created nature, created universe, creation, cycle, dance, date, descent, diet, drone, earth, eisteddfod, element, elementary particle, elementary unit, endless belt, endless round, everything that is, expanding universe, festivity, fete, file, filiation, fire, forgathering, forum, fundamental particle, gamut, gathering, get-together, gradation, housewarming, hum, hyle, hypostasis, levee, line, lineage, macrocosm, macrocosmos, material, material world, materiality, matter, meet, meeting, megacosm, metagalaxy, molecule, monad, monotone, natural world, nature, nexus, omneity, panel, party, pendulum, periodicity, physical world, powder train, progression, prom, pulsating universe, queue, quorum, rally, range, rank, reception, recurrence, rendezvous, reticulation, rotation, round, routine, row, run, scale, seance, sequence, series, session, shindig, sidereal universe, single file, sit-in, sitting, soiree, spectrum, steady-state universe, string, stuff, substance, substratum, succession, sum of things, swath, symposium, synod, system, the four elements, thread, tier, totality, totality of being, train, turnout, unit of being, universe, water, whole wide world, wide world, windrow, world, world without end

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ROGET THESAURUS

plenum

Substantiality

N substantiality, hypostasis, person, being, thing, object, article, item, something, a being, an existence, creature, body, substance, flesh and blood, stuff, substratum, matter, corporeity, element, essential nature, groundwork, materiality, substantialness, vital part, world, plenum, substantive, substantial, hypostatic, personal, bodily, tangible, corporeal, substantially, bodily, essentially.

Materiality

N materiality, materialness, corporeity, corporality, substantiality, substantialness, flesh and blood, plenum, physical condition, matter, body, substance, brute matter, stuff, element, principle, parenchyma, material, substratum, hyle, corpus, pabulum, frame, object, article, thing, something, still life, stocks and stones, materials, physics, somatology, somatics, natural philosophy, experimental philosophy, physicism, physical science, philosophie positive, materialism, materialist, physicist, somatism, somatist, material, bodily, corporeal, corporal, physical, somatic, somatoscopic, sensible, tangible, ponderable, palpable, substantial, objective, impersonal, nonsubjective, neuter, unspiritual, materialistic.

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